Conversion of hydrocarbons having a high boiling-point into hydrocarbons having a lower boilingpoint by destructive hydrogenation



Dec. 5, 1933.

R. H. GRlFFlTH 1,938,328 CONVERSION OF HYDROCARBONS HAVING A HIGH BOILING POINT INTO HYDROCARBONS HAVING A LOWER BOILING POINT BY DESTRUCTIVE HYDROGENATION 3 Sheets-Sheet l Filed Deo Om Ov Om,

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CONVERSION OF HYDROGARBONS HAVING A HIGH BOILING POINT INTO HYDROCARBONS HAVING A LOWER BOILING POINT BY DESTRUCTIVE HYDROGENATION Filed'Deo. l2. 193C 3 Sheets-Sheet 3 INVENTOR Q @mw l y l 1,938,328 UNITED STATES PATENT! OFFICE' Y coNvEBsroN oF mnocAnBoNs HAVING .A man BomNG-Pom'r INT0 Himno- Patented Dec. 1933 CABBONS -HAVING A LOWER BOILING- POINT BY DESTRUCTIVE HYDROGENA- Q 'rioN nanna Hsu Grimm, London, England/insegno:- to The Gas Light & Coke Company, London, England, a British company Application December 12, 1930, Serial No. 501,998, and in Great Britain January 25, 1930 j.

11 claims. (o1. 19e-"53) This invention relates to processes for the destructive hydrogenation of high-boiling hydrocarbons by treatment with hydrogen at an elevated temperature and pressure in the presence of a molybdenum catalyst and a promoter, with the formation of hydrocarbons having a lower boiling-point than the boiling-point of the hydrocarbon. Such processes will be referred to herein as destructive hydrogenation processes of the type described.

Instances or high-boiling hydrocarbons, the treatment of which is contemplated in this invention include coal tar, phenolic bodies obtained therefrom, natural petroleum, asphalt, bitumen, oils and oil fractions produced from these substances.

lvlany proposals have been put forward for the use or molybdenum in processes for the destructive hydrogenation oi hydrocarbons. In some cases, the molybdenum catalyst is to be used alone. Inothers an additional substance is to be used along with it. For example, it has been proposed to employ copper or gold in conjunction with molybdenum, the molybdenum and copper (or gold) being used in equimolecular proportions.

A further proposal has been to use aluminium oxide in equimolecular proportions with molybdenum. 1t is also known to'employ molybdenum oxide deposited in small quantities upon certain metals and metal alloys, or upon zinc oxide, magnesia, active carbon, silica and the like. Another proposal still has been to use with a molybdenum catalyst small quantities (for example up to 10%) of aluminium hydrate, copper, zinc, chromium and like additional substances capable of enhancing the activity of the catalyst.

l have investigated the use of promoter substances with molybdenum in destructive hydrogenation processes of the type referred to, and I have discovered that if a curve oi catalyst-activity be plotted, the abscissa representing the atomic proportion oi promoter used relatively to the molybdenum and the ordinates representing catalyst-activity in terms of percentage of hydrogenation product boiling b elow a certain temperature, for example, 180 C., such curve has in it, in the early part .of the curve, that is to say,

' generally between the 0% and 10% promoter percentage values, an acute local peak on either side of which the curve is less steep. This phenomenon is quite general we iind whatever the promoter employed.

The abscissa of such a local peak in a cusped or peaked curve formed by connecting points representing the catalytic activity for given ratios of promoter to molybdenum when such points are plotted for small increments oi.' less than 1 atom of promoter'per 100 atoms of molybdenum is called in this specication the peak-ratio of promoter to catalyst and the term peakratio range denotes the range of promoter proportions in the immediate vneighborhood of the peak-ratio itself.

I have discovered, therefore, that there is within the range of possible molybdenum-promoter ratios a smaller and more critical range (herein referred to as a peak-ratio range) which, ii selected, will give a materially higher promotive eiect than ratios elsewhere on the curve.

In some cases the curve has two peaks in it between which there is a sharp drop where usually the addition of promoter is positively disadvantageous.

According to the present invention, therefore, a process ot the type referred to ior the destructive hydrogenation of high-boiling hydrocarbons, is characterized by the selection and use oi a ratio of promoter to molybdenum which is within the peak ratio range or one of the peak-ratio ranges of the catalyst-activity curve herein before referred to.

The accompanying diagrams illustrate more or less approximately typical curves for several promoters.

Figure l shows the curve for silicon (that is to say a molybdenum catalyst-silicon promoter mixture) when treating a low-temperature tar;

Figure 2 shows the curve for boron when operating on an aromatic oil;

Figure 3 is the curve for boron when working with a low-temperature tar;

Figure a shows the curves for phosphorus (P) lithium (Li) and calcium (Ca), also when working on a low-temperature tar; and

Figure 5 shows, in diagrammatic form, apparatus adapted for carrying out the process o! the invention.

As will be seen the silicon and boron curves have two peaks. In the case of silicon there is a first peak between the atomic ratios 2:100 and 3.5:100 of promoter element to molybdenum, and further along the curve, a second peak between the ratios 5:10() and 7:100, and between these two peaks there is a drop in the curve where the use of the promoter is positively disadvantageous. The existence of a second peak is found .with a large number of promoters and the peaks shown in Figure 4 are all second peaks. Moreover, the existence or a depression in the curvevbetween the rst and second peaks where `theueeofa Oil.

promoter is positively disadvantageof general occurrence in those cases the activity curve comprises two peaks.

occurrence, intensity and position of the peakof the catalyst-activity curve has been depend upon the composition of the material being treated. This fact is illusmuresZandafIhusinthecase of the apexof theflrstpeakis situated at e 4.5% position along the whereas in the case of 'Figure 3, the apexofth ilrstpeakisat about the 5.3% posi- Ih Figure l, the raw material being treated 'low-temperature tar. In Figure 2, it was moter, for example, silicon will also .be found to exhibit a iirstpeak with most other promoters.

ture and pressure variations do not moet the podtion of either of the peaks of the catalyst-activity curve, but only the magnitude of the peak.

The second peak of the activity curve for a tiven promoter is found to be independent not only of the temperature and pressure employed in the reaction, but also of the raw material undergoing treatment. This is illustrated in the curvesshowninFigures2and3,where. as willbe seen, the apex of the second peak is at the same position inboth curves. Moreover, it is frequently found that the height of the second peak exceeds that of the ilrst. The importance of these two phenomena will be at once appreelated," and in the actual practice of the process, the preferred ratio used of promoter to molybdenum will generally be the optimum ratio of the second peak-ratio range. The positions of the peak-ratios and their extent in the curves depend upon the particular promoter used, but can be readily determined in any given case by a simple preliminary test. In this connection it will be appreciated, of course, that owing to theV steepness of the peaks in the curve in the neighborhood of the apex of the peak, the experiments to ascertain the exact position of the peak apex should be made with respective promoter percentages only slightly different from one another; otherwise the real optimum percentage of the peak may be missed. The extent of the peak-ratio range on either side of the apex of the peak may be taken, for the purposes of` determining the scope of the claims appended hereto, as limited to ratios at which the increase of activity due to the use of thepromoter is approximately or over of the maximum increase (at the apex of the peak).

The promoter may either be in the elemental form or in the form of an appropriate compound of the promoter element, for example, a reducible oxygen compound or a sulphide of the element. Similarly the molybdenum catalyst may either be molybdenum in the elemental form, .or a suitable compound of molybdenum, and the expressions, molybdenum catalyst and promoter element are to be understood accordingly.

Two or more promoters may be used together. A feature of the invention is the use as the promoter in the improved process, of one or more of the lighter metals, alkaline earth metals, metalloids or solid non-metallic elements (that is to say, for example, one or more elements of these-classes lighter in atomic weight than chromium), or their compounds. In this connection,

Lacasse however, it is to be understood that the use as the promoter of sulphur as such is excluded from the scope of the. invention, as sulphur is a substance which per se will not operate as a promoter in the process.

A further feature of the invention is the use in the improved process, of the promoters specifically mentioned above, namely, silicon, boron. lithium, phosphorus and calcium, or their compounds.

It has been found that the lighter elements of the classes referred to above, and in particular the promoters specifically mentioned, arevery effective in the process. Also, they lend themselves readily to the formation of accurately proportioned and homogeneous mixtures with the molybdenum catalyst. This is important, as will be appreciated from a perusal of the catalystactivity curves, for the peaks therein are very acute, and consequently even a slight inaccuracy in the ratio of promoter to molybdenum in the catalyst-promoter mixture, or a slight degree of non-homogenity of the mixture, may involve a very considerable lessening of the eifect of the promoter.

In this connection we may say that we have found it necessary in most cases to work within the fine limit of approximately 0.1% of the pre' determined optimum ratio (apex of peak) and that the usual methods employed for producing an accurately proportioned and homogeneous mixture of catalyst and promoter, namely, extensive mixed grinding and co-precipitation of the component elements of the desired mixture, have generally failed to give with certainty a degree of accuracy within the ne limits stated. This is particularly the case where the catalyst is a considerably heavier element than the promoter. The following method, however, of preparing a catalyst-promoter mixture for use in the improved process ofthe invention has been found to give highly satisfactory results in these respects.

A soluble salt of the promoter element is taken and dissolved in a small quantity of water. The resulting solution ls mixed into a. paste with a ne powder of the molybdenum catalyst. This paste is then forced through a die into threads or small pieces which are dried. In this method, instead of using a solution of a soluble salt of the promoter element, a colloidal suspension of the promoter element or an insoluble compound thereofmay be used.

When the promoter element is one which forms an acidic oxide, a convenient salt to use in the method aforesaid is the ammonium salt of this oxide; or the oxide itself can be used. When the promoter element forms a basic oxide, an organicacid salt, or a nitrate or a carbonate or vthe hydroxide of the promoter element may be employed.

The best results are obtained when the solubility of the promoter in water does not vary greatly with temperature variations, and also when the promoter is one which is not deliquescent.

As previously indicated herein, the molybdenum catalyst may be promoted by two or more promoter elements, or their compounds, used together. In this event, the relative proportions employed of the two or more promoters should be an appropriate compound of the proportions that would be requisite if the promoters in question were used alone with the molybdenum. For example, if one half of the optimum proportion Lacasse oi be employed, namely a proportion in which the atomic ratio oi molybdenum to lithium is about 10023.55, then, as at the optimum proportions the activities of lithium and phosphorus are approximately the same, an amount of phosphorus should be employed such that the atomic ratio of molybdenum to phosphorus in the mixture oi molybdenum, lithium and phosphorus, is about l:2.l. Similarly. if less lithium be used than the proportion stated above, viz, 3.55% correspondingly more phosphorus will be required, and, conversely, if more lithium be present less phosphorus will be needed to give the same effect.

@ne type oi apparatus suitable for carrying the present invention into effect is shown in diagrammatic torni in Figure in which l is a reser- Voir for the oil or tar to be treated, 2 is a. pump delivering the oil or tar to the electrically heated catalyst vessel 5 where it reacts with hydrogenatgas delivered by a compressor 3 from an inletpipe d. .after leaving the catalyst vessel 5 the products oi' the reaction pass into a condenser 6 and' thence into separators 'l and 9. Gas leaves the separators through pipes 8 and ll while liquid drawn ori from the system through pipe l0. The invention will now be 'iurther described reierenoe to several exemples oi the process, which are given purely by way of illustration.

Example .i

200 parte oi a low-temperature tar, topped to att C., are heated with hydrogen for one hour under a pressure of 200 atmospheres and at a temperature of 440 C. in the presence oi l0 parts catalyst consisting of a homogeneous mixture of inolybdio acid and silica in the atomic ratio, molybdenum to silicon, or 100:3.

The product comprised about 24 parts of water and about llt parts of oil, of which 48.5% boiled below l00 C. The parts stated are by weight both in this example and in the examples i'ollowing.

Example il' The same tar was treated under the same conditions oi temperature, pressure and quantities, but with a molybdic acid--silica catalyst in which the atomic ratio of molybdenum to silicon wasI 100 5.4i. The product comprised 24 parts of water and approximately 120 parts of oil, 49% of which boiled below 3.30" C.

Eample III The same tar was treated, again under the same conditions of temperature, pressure and quantities, as Example I but with a molybdic acid-silica. catalyst in which the atomic ratio oi molybdenum to silicon was 100:4.4. The prod.- uct comprised parts of water and approximately 130 parts or oil, of which 28% boiled below itil" C.

Example IV The same tar treated under like -conditions again but in the presence of molybdenum acid alone, yieldedva product consisting of 14 parts of water and approximately 138 parts of oil, of which 33% boiled under 180 C.

lt will be observed from the above examples and by reference to the accompanying diagrams that when the ratio of catalyst to promoter is within either of the peaks of the catalyst-activity curve for silicon, the yield of light oil is considerably higher than when the hydrogenation treatment is carried out in the absence of a promoter. lt will further be noted from Example Ill that the yield is delinitely less when the ratio of promoter to catalyst is between the two peaks of the curve than it would be if the molybdenum catalyst were used alone; that is to say, in the absence of a promoter. Finally, it will be seen that the yield is greater when the catalyst promoter ratio is a ratio in the second peak of the curve.

Example V 200 parts of a low-temperature tar, topped to 200 C. were heated with hydrogen for one hour at 440 C. and under a pressure of 200 atmospheres in the presence of l0 parts of a molybdic acid-boris acid catalyst in which the atomic ratio of molybdenum toboron was 10028.?. The product comprised parts oi water and approximately lll parts of oil, of which 51% boiled below 180 C.

Esempio Vl a The same tar similarly treated but with molybdic acid-lithium oxide, molybdic acicl-calciumA oxide and molybdic acid-phosphorus oxide catalyst mixtures, in which the atomic ratios of molybdenum to lithium, molybdenum to calcium and molybdenum. to phosphorus were respectively 100:71, l00:'l'.6 and l00:fi.25 yielded in the process approximately l05 parts of oil, 49.5% or which boiled below leo C., 122 partswith a percentage of 54.5 boiling below 180 C., and iBS parts with a percentage or? sill boiling below 130 C.

Eixample Vil 200 parts of an aromatic hydrocarbon gas-oil were heated in the presence of l0 parte of a rnolybdic acidboric acid catalyst in which the atomic ratio of molybdenum to boron was 100:8.75. The yield was approximately M5 parts of an oil, oi which boiled below 180 C.

Example VIH A light creosote oil was heated inthe same quantities in the presence of a. molybdic acidboric acid catalyst in which the atomic ratio of molybdenum to boron was :8.'75. The product compris/es 10 parts of water and approximately 147 parts of oil, of which 56% boiled below 180 C.

Ejemplo IX 200 parts of crude naphthalene when similarly treated yielded approximately 143 parts of oil, of which 48% boiled below 180 C. and consisted largely ,of benzene, toluene and xylene.

Example X An oil obtained by distillation of Scottish shale, treated, again under like conditions, gave approximately 156 parts of oil containing 54.5% boiling below 180 C.

Example XI flcation and claims denotes a catalyst body composed of or containing molybdenum; that, similarly, the term lithium promoter" denotes a promoter body composed of or containing lithium. and that analogous expressions have the like meaning.

I claim:

1. A process for the destructive hydrogenation of high boiling hydrocarbons or derivatives thereof which consists in heating the hydrocarbons at a temperature of the order of 440 C. with hydrogen under a pressure of the order of 200 atmospheres in the presence of a catalyst mixturev comprising molybdenum and a promoter therefory 3. A process for the destructive hydrogenationY of high-boiling hydrocarbons or derivatives thereof, which consists in heating the hydrocarbon at a temperature of the order of 440 C. with hydrogen under a pressure of the order of 200 atmospheres in the presence of a catalyst mixture comprising modybdenum and a promoter therefor consisting of silicon, the silicon and molybdenum being in peak-ratio proportions as herein defined.

4. A process for the destructive hydrogenation of high boiling hydrocarbons or derivatives thereof which consists in heating the hydrocarbon at a temperature of the order of 440 C. with hydrogen under a pressure of the order of 200 atmospheres in the presence of a catalyst mixture comprising molybdenum and a promoter therefor consisting of silicon, the ratio of silicon to molybdenum being within the second peak of the catalyst activity curve herein referred to.

5. A process for the destructive hydrogenation of high boiling hydrocarbons or derivatives thereof which consists in heating the hydrocarbon at a temperature of the order of 440 C. with hydrogen under a pressure of the order of 200 atmospheres in the presence of a catalyst mixture comprising molybdenum and a promoter therefor consisting of silicon, the proportion of silicon to molybdenum being between 5 and 6 atoms per 100 atoms of molybdenum.

6. A process for the destructive hydrogenation of high-boiling hydrocarbons or derivatives thereof which consists in heating the hydrocarbon at a temperature of the order of 440 C. with hydrogen under a pressure of the order of 200 atmospheres in the presence of a catalyst mixture comprising molybdenum and a promoter therefor consisting of lithium, the lithiumv and molybgiim being peak-ratio proportions as herein de-l 7. A process for the destructive hydrogenation of high-boiling hydrocarbonsor derivatives thereof which consists in heating the hydrocarbon at a temperature of the order of 440 C.' with hydrogen *underV a pressure of the order of 300 atmospheres in the presence of a catalyst mizture comprising molybdenum and a promoter therefor consisting of lithium, the ratio of lithium tc molybdenum being within the second peak of the catalyst-activity cm've herein referred to.

8. A process for the destructive hydrogenation of high-boiling hydrocarbons or derivatives therea temperature of the order of 440 C. with hydro- 4 gen under a pressure of the order of 200 atmospheres in the presence of a catalyst mixture comprising molybdenum and a promoter therefor consisting of boron, the boron and molybdenum being in peak-ratio proportions as herein defined.

10. A process for the destructive hydrogenation of high-'boiling hydrocarbons or derivatives thereof which consists in heating the hydrocarbon,at a temperature of the order of 440 C. with hydrogen under a pressure of the order of 200 atmospheres in the presence of a catalyst mixture comprising molybdenum and a promoter therefor consisting of boron, the 'ratio of boron to molybdenum being within the second peak of the catalyst-activity curve herein referred to.

11. A process for the destructive hydrogenation of high-boiling hydrocarbons or derivatives thereof which consists in heating the yhydrocarbon at a temperature of the order of 440 C. with hydrogen under a pressure of the order of 200 atmospheres in the presence of a catalyst mixture comprising molybdenum and a promoter therefor consisting of boron, the proportion of boron to' molybdenum being between 8 and 9 atoms per atomsof molybdenum.

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